High temperature lubricants



United States Patent 0 20 Claims. (or. sea-2s The present invention relates to high temperature inorganic lubricants, more particularly, to a lubricant composition of inorganic alkali metal and ammonium phosphates which are free from oils and fats and to which are added viscous soluble potassium polyphosphates, and a method of lubricating surfaces subjected to high temperatures.

rganic materials such as fats, oils and soaps are generally used as lubricants. Such organic lubricants, however, are limited to temperatures below 200 C. and only in exceptional cases can these lubricants be used at temperatures as high as 230 C. Where high temperatures preclude the application of organic lubricants, graphite is generally used. In applications where high temperatures and pressures are present, such as in various metal-working processes, the graphites which are used contain a large quantity of ash. The ash, however, has the effect "of a parting compound as is evidenced by the deposition of ashes on the material being worked. In addition, this ash may become welded or fused. Consequently, the tools used may be damaged and the surface of the worked material may be subjected to scoring.

One solution has been to employ on the surfaces of the metal to be worked a vehicle or carrier coating in an elfort to produce a strong adherence of organic lubricants to the surface. Such vehicle coatings comprised salts or salt mixtures. In addition, phosphate coatings were used as vehicles with such phosphates being produced in the conventional manner by phosphatizing. Further, lubricating coatings on metals were also produced by the action of a dispersion or a solution of aliphatic phosphates conraining? to 18 carbon atoms. However, these described lubricants were also limited to the aforementioned low temperatures because of the decomposition of the organic substances.

Other lubricants, such as viscous aqueous solutions of polyphosphates, Kurrols salts or metaphosphoric acid whose lubricating effect depends on the viscosity of the solution were also limited to the use at low temperatures.

It has also been proposed to use salts for lubrication at high temperatures wherein the salts would melt on the surface of the material being worked and the resulting residue melt would have a lubricating effect. However, not all of these used salt melts had a lubricating effect. Tests were conducted which proved that using borate of soda alone or in a mixture of oil as a lubricant in the production of seamless tubes caused a gumming up and a shut-down of the process. Also, the use of crude sodium chloride caused abrasion of the material and deposits at some spots so that furrows in the material were formed,

In addition, it was not possible to use any salt mixtures since such mixtures had the same effect. For example, a molten salt mixture of 22% BaCl 37% NaCl and 41% KCl and melts of cryolite had the same effect.

One form of high temperature lubricant which has been known comprises a water-soluble lubricant which has a simultaneousdescaling effect and which becomes soft at the comparatively low temperature of 300 C. This material adheres to a surface up to temperatures of about 1000" C. This lubricant did not contain any abrading or parting compounds and comprised particular Car dildhfid-E Patented .lune l, lQfiS "ice proportions of alkali metal phosphate and alkali metal tetraborate. The lubricant has a descaling effect by forming boundary layers which, in turn, have a lubricating effect. However, this lubricant did not contain a viscous soluble potassium polyphosphate.

Another proposed lubricant for the working of low melting alloys were glasses containing alkali metal oxide, phosphorous pentoxide and alumina (aluminum oxide). Such glasses are virtually insoluble in water because of the presence of aluminum oxide therein. Further, it is extremely difficult to remove this lubricant from a metallic surface, particularly from the interior of tubes. These same disadvantages are also present when using silicate glasses or slags as high temperature lubricants. Such lubricants require a post mechanical treatment by sandblasting or the application of a particular chemical after treatment with hydrofluoric acid. Further, the use of such enamels and glasses requires the previous descaling of the metal surface.

In many cases Where such lubricants were applied it was found to be difiicult and occasionally impossible to uniformly apply these lubricants to the working surfaces. Either the lubricant did not sufficiently adhere to the surface or its nature was such that it could not be uniformly distributed. As a result, the lubrication was poor together with many other attendant difficulties. It was found that when more dilute aqueous solutions of inorganic lubricants were applied to the surface, insufficient lubricant remained on the surface after the water evaporated. This remaining lubricant was insuflicient to perform a proper lubricating process.

These dithculties could not be overcome merely by the adding of binding agents since water glass, for example, forms insoluble silicate residues on the materials. Organic binding agents could not be used because they decompose at high temperature and they also had a carburizing effect on tools and work pieces which resulted in metallurgical changes in the tools and work pieces.

In view of the above described difiiculties in lubricating, considerable interest existed in lubricants which are watersoluble but which do not contain any organic substances and could be applied as a viscous solution. Suilicieut quantities of such lubricants would adhere to the surface when applied to a cold surface which is subsequently heated or when initially applied to a hot surface.

It is therefore the principal object of this invention to provide a novel and improved lubricant composition for use at high temperatures.

It is another object of this invention to provide a novel and improved method of lubricating surfaces subjected to high temperatures.

It has been discovered that oiland fat-free lubricants comprising inorganic alkali metal and ammonium phosphates can be applied as an aqueous solution on the surface to be lubricated wherein the water will evaporate and the resulting residue melt will provide sufiicient and adequate lubrication. The disadvantages of prior art lubricants as described previously can be avoided by ren dering the lubricating solution highly viscous by admixing therewith viscous soluble potassium polyphosphate so as to form a viscous solution. The salts of the lubrieating solution are so selected that they form, after evaporation, a mixture in the range of the eutectic composition. Such salts are alkali metal phosphates alone or together with one or more of the following: alkali metal borates, alkali metal sulfates, alkali metal chlorides, alkai metal fluorides, or alkalimetal chromates. The alkali metal cations are preferably sodium and potassium, but it is also possible to use other alkali metal cations as well as the ammonium ion. A portion of the alkali metal or ammonium salts can be replaced by salts of bivalent phosphate to' be dissolved in Water. 'lubricant of this invention additionally contains a water- 'herence of the lubricant also at low temperatures.

which residue will adhere thereto.

metals particularly magnesium, manganese.

Viscous soluble potassium polyphosphate has the characteristic of rendering a solution viscous. This viscous solution can then be easily and uniformly applied to working surfaces. After the water has evaporated, the remaining residue melt will also be viscous but will have a different viscosity than the solution as originally applied. This melt will readily adhere to the surface even at high calcium, Zinc, and

temperatures and will satisfactorily lubricate the surface.

The viscosity of a 10% solution of the lubricant of this invention will be about 8-20 centipoises, preferably between 10-20 centipoises, measured in a rotation viscosimeter with a shearing gradient of 700 (secondsat a temperature of 50 C.

Viscous soluble potassium polyphosphate is insoluble in pure water. Therefore, the presence of other cations, such as sodium, is necessary for the potassium poly Accordingly, the

soluble salt with another cation other than potassium, preferably a sodium salt such as a sodium orthophosphate or a'condensed sodium phosphate.

The aqueous solutions of the lubricant of this invention can be applied by brushing, spraying, or in any other suitable way.

It must be borne in mind that the lubricant of this invention and method of application thereof are not the same as the previously proposed use of aqueous viscous solutions having a phosphate base. These previously proposed solutions were for low temperature applications,

effect from the deposition, the Water in the solution evaporates and the lubricant residue will adhere as a film to the surface. No crystallizing of the components of the lubricant or a breaking down of the solution will occur because of the high viscosity of the solution. The lubricating effect per se is accomplished by the melted eutectic mixture. The viscosity of the residue melt which depends on the temperature is independent of the viscosity of the solution.

Several specific examples of lubricant compositions in accordance with the present invention will next be described.

Lubricant I:

55-69%, preferably 60-68% by Weight of P 14-35%, preferably 17-28% by weight of Na O; 5-27%, preferably 921% by weight of K 0.

(These percentages are after the lubricant has been freed of the water of constitution.)

7 About 5-100% of K 0 is used as viscous soluble potassium polyphosphate.

This lubricant is particularly applicable for medium temperature lubrication. The lubricant begins to melt at 200-250? C. and remains amelt up to 400 C. From 400 C. to; 500 C. the lubricant-is not amelt but above 500." 'C; again becomes a melt. If 1-10%, preferably '1' 15%', of the sodium and/ or potassium is replaced by bivalent metals such as magnesium, Zinc or manganese, the

lubricant will remain a melt in the range of 400-500 C.

1 The residue melt will have a lubricating effect well into higher temperature ranges. I

Less than of the water will remain in this lubricant the sticking together of the steel and mandrel. I

' Lubricant III:

.Lubricant V:

between ZOO-400 C. Above this temperature range, however, all of the water will be evaporated.

In all of the subsequent examples (II-VII), the Water is introduced as water of constitution and Water of crystallization. All of this water is evaporated prior to obtaining the lubricating effect.

Lubricant II:

51.11% by weight of P 0 1.83% by weight of B 0 24.93% by weight of Na O; 5.42% by weight of K 0; 1.46% by Weight of MnO; and 15.25% by weight of H 0,

wherein the potassium is in the form of a viscous soluble potassium polyphosphate. This lubricant is applied as a highly viscous slurry of about 30% lubricant mixture and water.

Lubricant II, according to the present invention, has been used particularly in the fabrication of seamless tubes. During a process of diagonally rolling high-grade alloy steel over a mandrel there was a high degree of waste since, many times, it was impossible to remove a jammed mandrel from the steel. When it was possible to remove the mandrel from the billet, the mandrels were damaged so that it was only possible to roll an average of 3.8

billets over a single mandrel. Accordingly, by applying a lubricant as taught by the present invention on the head of the mandrel it was possible to roll as manyas 50 illets over a single mandrel since the lubricant eliminated 51.15% by weight of P 0 1.82% by Weight of B 0 21.02% by weight of Na O; 5.98% by weight of K 0; 1.46% by Weight of ZnO;

5.15% by weight of NH and 13.42% by weight of H 0.

All of the K 0 is introduced as viscous soluble potassium polyphosphate. In this lubricant it is possible to substitute sulfuric acid, hydrofluoric acid, or chromic acid (C1O3) for the B 0 in the same proportions.

TLubricant IV:

56.61% by weight of P 0 23.74% by weight of Na O;

9.02% by weight of K 0; and

10.63% by weight of H 0.

56.44% by weight of P 0 22.54% by weight of Na O; 8.56% by weight of K 0; I

0.40% by weight of MgO;

0.62% by weight of MnO; and

11.44% by weight of H 0.

In lubricants IV and V about 66% of the K 0 is introduced as a viscous soluble potassium polyphosphate and the remainder as potassium orthophosphate (KH PO By the use of the lubricant of this invention, particularly lubricants III, IV and V, preferably applied as 10% solutions, it was possible to greatly improve the process of forming austenitic steel tubes by forging rolls by rolling pierced billets. This process essentially comprises intro- 7 ducing a mandrel of uniform diameter into a pierced hot billet.- j The billet with the mandrel therein is' then passed reciprocatingly throughforging rolls. One form -.of forging rolls is known as the Pilger tube mill vwhich'is largely used for forminglarge diameter seamless tubing by rolling the billet off of the end of a mandrel. The Pilger tube mill performs a rolling and forging process by eccentrically positionedrollers. A seamless tube is then formed progressively from the billet with the, tube being rolled over the entire length of the mandrel. The mandrel becomes red hot during this process and must be removed from the tube. In many cases it was diflicult to remove the mandrel from the tube so that during the removal thereof the finished tube was damaged. In addition, it was generally necessary to use a pressure of up to 200 atmospheres for separating the tube from the mandrel. It was found that after lubricating the mandrel with the lubricant of this invention a separating pressure of only 20 to 60 atmospheres was required and the binding of the mandrel and the tube was virtually omitted.

It is also possible to introduce agents having a higher borate content, e.g., 10-28% by weight of P 18-30% by weight of B 0 18-21% by weight of Na O, l-3% by weight of K 0, 03-08% by Weight of Mn(), and 2940% by weight of water of crystallization and water of constitution.

Lubricant VI:

27.23% by weight of P 0 18.50% by weight of B 0 20.70% by weight of Na O; 3.00% by weight of K 0; 0.77% by weight of MnO; and 29.80% by weight of H 0.

Lubricant VII:

10.98% by weight of P 0 29.20% by weight of B 0 18.06% by weight of Na O; 1.45% by weight of K 0; 0.31% by weight of MnO; and 40.00% by weight of H 0.

All of the K 0 is introduced in the form of viscous soluble potassium polyphosphate in both lubricants VI and VII. Lubricants VI and VII are applied as 2-3% solutions in water. Here also the solutions are viscous and remain viscous after the evaporation of the water to adhere to the surface. This lubricant is applied in lower concentrations since Na B 0 is not particularly soluble in water.

This solution is preferably applied by being sprayed twice on the surface. After the first spraying, the water is evaporated. Subsequently, the solution is sprayed again on the same surface. The viscosity of the solution is important, because if not viscous, the solution will flow off 1 of the surface when it is a mandrel or the like.

Very good lubricating results can also be obtained when using the lubricant of this invention, particularly lubricants VI and VII, in a process of forming a seamless tube wherein a red hot billet is mounted on the head of a mandrel of uniform diameter and the mandrel and the billet are pushed through an arrangement of openings or idler rollers which progressively decrease in size. The edges of these openings or the rollers have the effect of pushing the softened metal over the head of the mandrel and over the entire length thereof and it is necessary that the friction be reduced to a minimum. The process is similar to that of a conventional extruding process for forming tubes. In such extrusion processes the tubes may be formed from either solid or hollow (pierced) billets. When using the lubricants of this invention, particularly VI and VII, in this process the formation of deposits and scoring, such as resulting from oil graphite lubrication, were avoided. In addition, when applying the lubricant of this invention as a viscous solution in an even layer the consumption thereof is quite low. Therefore, the use of this lubricant is less expensive than lubrication with a mixture of oil and graphite.

In all of the above lubricants all of the Water, i.e., water of solution, water of constitution, and water of crystallization, is evaporated from the applied solution at about 400-500 C.

In addition to the above described applications, the Inbricant of this invention can be successfully used in many other high temperature operations, several of which will be described.

This lubricant has also been successively used on dies in drop forging such as employed in the forging of flywheels. When a lubricant comprising a mixture of oil and graphite was used the dies were subjected to the formation of numerous cracks therein which eventually resulted in the destruction of the dies. The use of the lubricant of this invention resulted in doubling the service life of the dies. Further, it was only necessary to thoroughly clean the worn dies but it was not necessary to replace them completely.

This invention can also be applied to the extruding of ferrous and non-ferrous metals, particularly in the formation of tubing. With known lubricants, in the formation of copper tubes, only the core of the copper billets can be used in the {formation of the tube and the exterior walls of the billet were left in place. By using the lubricants of this invention, however, it was possible to utilize the entire billet so that Waste and scrap were considerably reduced. Further, the output was greatly increased since the time-consuming process of removing the billet shells was avoided.

The lubricant of this invention is a high temperature lubricant which can be successfully used in many other high temperature zones (about 1000" 0.). While the greatest application of this lubricant is in the field of metal rolling and forming it can also be used as a lubricant for the doors of open hearth furnaces and many other atmospheres where high temperatures are encountered.

It is therefore apparent that the present invention has provided a method and substance for lubricating working surfaces in various metal-forming operations. The use of this lubricant has resulted in a decrease in lubrication costs and in an improvement in the entire metal-working process since the output was increased and waste considerably reduced.

Thus it can be seen that the present invention discloses a high temperature lubricant and a process of lubricating surfaces subjected to high temperatures. The preferably used lubricant essentially consists of 50-90% of alkali metal phosphate and 10-50% of alkali metal borate wherein 2-20% of the mixture by weight is potassium polyphosphate. This lubricant preferably comprises 70-80% of alkali metal phosphate and 20-30% of alkali metal borate with 10% of the mixture by weight being potassium polyphosphate.

It will be understood that this invention is susceptible to further modification and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

What is claimed as this invention is:

'1. An oiland fat-free lubricant for application as an aqueous solution to a metallic surface to be lubricated where it dries and the resulting residue melt produces a lubricating effect, and consisting essentially of a viscous soluble potassium polyphosphate and at least one inorganic monovalent salt selected from the group consisting of alkali metal phosphate and ammonium phosphate and at least one salt selected from the group consisting of magnesium phosphate, calcium phosphate, zinc phosphate, manganese phosphate, alkali metal borate, ammonium borate, magnesium borate, calcium borate, zinc borate, manganese borate, alkali metal sulfate, ammonium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, manganese sulfate, alkali metal chloride, ammonium chloride, magnesium chloride, calcium chloride, zinc chloride, manganese chloride, alkali metal fluoride, ammonium fluoride, magnesium fluoride, calcium fluoride, zinc fluoride, manganese fluoride, alkali metal chromate, ammonium chromate, magnesium chromate, calcium chromate, zinc chr'omate, manganese chromate, and mixtures thereof, with the provision that a cation other than potassium be contained in at least one of said salts, and'the ratio of the salts being such that a mixture in the range of the eutectic composition is formed after evaporation of the water.

2. A process of lubricating a metallic surface subjected to high temperatures, comprising the steps of mixing with water a viscous soluble potassium polyphosphate in substantially eutectic proportions with at least one inorganic monovalent salt selected from the group con sisting of alkali metal phosphate and ammonium phosphate and at least one salt selected from the group consisting of magnesium phosphate, calcium phosphate, zinc phosphate, manganese phosphate, alkali metal borate, ammonium borate, magnesium borate, calcium borate, zinc borate, manganese borate, alkali metal sulfate, ammonium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, manganese sulfate, alkali metal chloride, am monium chloride, magnesium chloride, calcium chloride, zinc chloride, manganese chloride, alkali metal fluoride, ammonium fluoride, magnesium fluoride, calcium fluoride, zine fluoride, manganese fluoride, alkali metal chromate, ammonium chromat'e, magnesium chromate, calcium chromate, zinc chromate, manganese chromate, and mixtures thereof, with the provision that a cation other than potassium be contained in at least one of said'salts applying the resultant viscous aqueous solution of the mixture to said metallic surface, and drying the mixture on the surface so that the remaining residue adheres to the surface as a lubricant. a 3. In oiland fat-free inorganic lubricants for application as an aqueous solution to a metallic surface to be lubricated when it dries and the resulting melt produces a lubricating effect, and comprising a mixture of an inorganic phosphate selected from the group consisting of an alkali metal phosphate and ammonium phosphate, and a metallic compound selected from the group consisting of monovalent and divalent metal salts containing a cation other than potassium and a viscous soluble potassium polyphosphate mixed therewith, the ratio of the salts being such that a substantially eutectic composition is formed after evaporation of the water.

4. A process of lubricating a metallic surface subjected to high temperature with an oiland fat free lubricant, comprising the steps of mixing in substantially eutectic proportions a viscous soluble potassium polyphosphate with an inorganic phosphate selected from the group consisting of an alkali metal phosphate and ammonium phosphate and also with a metallic compound selected from the group consisting of monovalent and divalent metal salts containing a cation other than potassium, and applying a viscous aqueous solution of the mixture to the surface, and drying the mixture on the surface so that the remaining residue adheres to the surface as a lubricant.

5. An oiland fat-free lubricant as claimed in claim 1 wherein said potassium polyphosphate comprises about 220% by weight of the mixture.

6. An oiland fat-free lubricant as claimed in claim 1 wherein said potassium polyphosphate comprises about 10% by weight of the mixture.

7. An oiland fat-free lubricant for application as an aqueous solution to a metallic surface to be lubricated in the proportions of said substances are 60-68% by weight of P 0 17-28% by weight of Na O and 92l% by weight of K 0. V a

10. A process of lubricatinga metallic surface which is subjected to high temperaturesand comprising applying to thesurface an aqueous mixture of phosphates, analyzing 55-69% by weight of P 0 14-35% by weight of Na O and 5-27% by Weight of K 0 with 5-100% of the K 0 being in the form of viscous soluble potassium polyphosphate.

11. A process of lubricating a metallic surface which is subjected to high temperatures and comprising applying to the surface an aqueous mixture of phosphates, analyzing'60-68%'by weight of P 0 17-28% by weight of Na O and 9-2l% by weight of K 0 with 5-100% of the K 0 being in the form of viscous soluble potassium polyphosphate. 7

12. A process for lubricating a metallic surface at high temperatures and comprising applying 'to the surface a viscous aqueous solution analyzing 55-69% by weight of P 0 14-35% .by weight of Na O and 527% by weight of K 0, 5-100% of the K 0 being in the form of viscous soluble potassium polyphosphate and evaporating the water from the applied solution so that the remaining residue melt will adhere to the .surface 'as a lubricant.

13. A solution of a high temperature lubricant consist- .ing essentially of a viscous solution analyzing -28% by weight of P 0 18-30% by weight'of'B o 18-21% by weightof Na O, l-3% by weight of K 0, 03-08% by weight of MnO and 29-40% by weight .of H 0, the K 0 being in the form of viscous soluble potassium polyphosphate.

14. A solution of a high temperature lubricant consisting essentially of a viscous solution of 27.23% by weight analyzing P 0 18.50% by weight of B 0 20.70% by weight of N320, 3.00% by weight of K 0, 0.77% by weight of MnO and 29.80% by weight of H 0, the K 0 being in the form of viscous soluble potassium polyphosphate.

15. A solution of a high temperature lubricant con- 1 sisting essentially of a viscous solution analyzing 10.98% by weight ofP O 29.20% by weight of 3 .0 18.06%

by weight of N320, 1.45% by weight of K 0, 0.31 by weight of MnO and 40.00% by weight of H 0, the K 0 I being in the form of viscous soluble potassium polyphosphate.

16. A high temperature lubricant consisting essentially of a mixture of 50-90% alkalimetal phosphate 7,

and 10-50% of alkali metal borate wherein 2-20% by weight of the mixture is viscous soluble potassium poly- 'phosphate, and at least a portion of the alkali metal cation'is other than potassium. V

17. A high temperature lubricant consisting essentially of a mixture of 70-80% alkali metal phosphate and -30% of alkali metal bo-rate wherein 2-20% by weight of the mixture is viscous soluble potassium polyphosphate, and'at least a portion of the alkali metal cation where it dries and the resulting residue produces a lubrieating effect, and consisting essentially of a mixture of phosphates, analyzing 55-69% byweight of P 0 14- by weight of Na O and 5-2'7% by weight of K 0, with 5-10()% of the K 0 being in the form of viscous soluble potassium polyphosphate,

' 8. An aqueous solution of an oiland fat-free lubricant for application as an'aqueous solution to a metallic surface; to be lubricated where it dries and the resulting residue produces a lubricating effect, and consisting essentially of a mixture. of phosphates, analyzing -69% by weight of P 0 14-35% by weight of Na O and 5- 27% by weight of K 0, with 5-100% of the K 0 being in the form of viscous soluble potassium 'p'olypliosphate, said mixturecontaining-both water of constitution and a water of crystallization. V

9. A solution of lubricant asclaimed in claim s where-i a is other than potassium.

18. A high temperature lubricant consisting essentially of a mixture of 70-80% alkali metal phosphate 2 and 20-30%" of alkali metal borate wherein 10% by weight of the mixture is viscous soluble potassium polyphosphate, and at least a portion of the alkali metal cation is other than potassium.

19; A, high temperature lubricant consisting essen tially of a mixture of 50-90% alkali metal'phosph'ate and 10-50% of alkali metal borate;wherein.2-20% by weight of the mixture. is viscous soluble potassium polyphosphate, 1;1 0% of the alkali metal being replaced by a a bivalent metal selected from the. group consisting of magnesium, calcium, zinc,jand manganese.

20L A high temperature lubricant consisting essen- I tially of a mixture of 50 %*alkali metakphosphate and I D- 50% ofalkali metal boratej wherein 2-20% by weight of the mixture is viscous soluble potassiumpoly- 9 phosphate, '1-5% of the alkali metal being replaced by a bivalent metal selected from the group consisting of magnesium, calcium, zinc, and manganese.

References Cited by the Examiner UNITED STATES PATENTS 1 0 FOREIGN PATENTS 594,265 3/60 Canada. 1,050,486 2/59 Germany.

815,355 6/59 Great Britain.

DANIEL E. WYMAN, Primary Examiner.

JULIUS GREENWALD, Examiner. 

1. AN OIL- AND FAT-FREE LUBRICANT FOR APPLICATION AS AN AQUEOUS SOLUTION TO A METALLIC SURFACE TO BE LUBRICATED WHERE IT DRIES AND THE RESULTING RESIDUE MELT PRODUCES A LUBRICATING EFFECT AND CONSISTING ESSENTIALLY OF A VISCOUS SOLUBLE POTASSIUM POLYPHOSPHATE AND AT LEAST ONE INORGANIC MONOVALENT SALT SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL PHOSPHATE AND AMMONIUM PHOSPHATE AND AT LEAST ONE SALT SELECTED FROM THE GROUP CONSISTING OF MAGNESIUM PHOSPHATE, CALCIUM PHOSPHATE, ZINC PHOSPHATE, MANGANESE PHOSPHATE, ALKALI METAL BORATE, AMMONIUM BORATE, AMGNESIUM BORATE, CALCIUM BORATE, ZINC BORATE, MANGANESE BORATE, ALKALI METAL SURFATE, AMMONIUM SULFATE, MAGNESIUM SULFATE, CALCIUM SULFATE, ZINC SULFATE, MANGANESE SULFATE, ALKALI METAL CHLORIDE, AMMONIUM CHLORIDE, MAGNESIUM CHLORIDE, CALCIUM CHLORDE, ZINC CHLORIDE, MANGANESE CHLORE, ALKALI METAL FLUORIDE, AMMONIUM FLUORIDE, MANGNESIUM FLUORIDE, CALCIUM FLURORIDE, ZINC FLUORIDE, MANGANESE FLUORIDE, ALKALI METAL CHROMATE, AMMONIUM CHROMATE, MAGNESIUM CHROMATE, CALCIUM CHROMATE, ZINC CHROMATE, MANGANESE CHROMATE, AND MIXTURES THEREOF, WITH THE PROVSION THAT A CATION OTHER THAN POTASSIUM BE CONTAINED IN AT LEAST ONE OF SAID SALTS, AND THE RATIO OF THE SALTS BEING SUCH THAT A MIXTURE IN THE RANGE OF THE EUTECTIC COMPOSITION IS FORMED AFTER EVAPORATION OF THE WATER. 